emc2's website
My understanding is that WB-8 is a copper coil pulsed machine. at .8T (peak) it may be enough for B11.mvanwink5 wrote:The WB-8.1 navy contract does include evaluation of scaling for coil size and B field, so what B field increase would provide adequate B-11 fusion for concept validation, 3T? Would a B field of 3T imply SC coils?
For continuous operation of a sub net power machine I'd go with 3T SC coils.
If I wanted net power I'd go for 10T @ 1 m bore. Or possibly 20 T @ .5 m bore. (same coil current - more intercepted area). At constant amp-turns B^4 R^3 scaling favors smaller machines. Now about those losses.....
Engineering is the art of making what you want from what you can get at a profit.
Wink,
Ultimately, the question is acceptable ion loss, but the energy balance of a Polywell is supposed to be very strongly dependent on electron loss.
Electron loss to the outer chamber walls ought to be a non-issue because the magrid is the only anode in the device, so improvments in the magrid to decrease losses are a great key to the operation. In principle, any electrons lost out corner cusps just come right back.
The question that has been raised is, would not ions follow the electrons right out the cusps? An ion outside the magrid is doomed to go to the walls. If this is occurring, it is a leak from the ion population, and it hurts the performance of the device. This is a fair question, but not one I think will be answered short of experiment. Is the loss trivial, acceptable, or deadly?
I see a lot of ports on the WB8 chamber illustrations positioned where instruments could analyze cusp losses.
Ultimately, the question is acceptable ion loss, but the energy balance of a Polywell is supposed to be very strongly dependent on electron loss.
Electron loss to the outer chamber walls ought to be a non-issue because the magrid is the only anode in the device, so improvments in the magrid to decrease losses are a great key to the operation. In principle, any electrons lost out corner cusps just come right back.
The question that has been raised is, would not ions follow the electrons right out the cusps? An ion outside the magrid is doomed to go to the walls. If this is occurring, it is a leak from the ion population, and it hurts the performance of the device. This is a fair question, but not one I think will be answered short of experiment. Is the loss trivial, acceptable, or deadly?
I see a lot of ports on the WB8 chamber illustrations positioned where instruments could analyze cusp losses.
Yes, I've made that point as well. The other scaling questions are so much more important, why screw around with a new geometry at this point when it isn't even an order of magnitude?Tom Ligon wrote:In fact, a factor of 3-5 could be made up by making the devices just a pinch larger. The success of the demo reactor will not be judged by a factor of 3-5. If it makes only 20 MW instead of 100 MW, but you know you can expand it 10% and make up the difference, no big deal. If a cubic WB-D comes in a little low, they know they have a few tricks left, including a dodec magrid.
They mean from WB-7 (.1T) to WB-8 (.8T). They're not building another machine with new coils, just modifying WB-8.The WB-8.1 navy contract does include evaluation of scaling for coil size and B field,
Nebel seems to think so. I'm not sure what the real challenge is though, since voltage is generally easy in IEC -- has anyone ever tried with a fusor? Is the reaction rate just too low to get detectable alphas in a fusor? I wonder if it could be done with WB-7. (My guess is density is too low for detectable alphas at those sizes.)My understanding is that WB-8 is a copper coil pulsed machine. at .8T (peak) it may be enough for B11.
When I saw ports at the cusps my first thought was "alphas!" I'm guessing .8T is enough to corral a good number of them in that direction, though I should really do the math.I see a lot of ports on the WB8 chamber illustrations positioned where instruments could analyze cusp losses.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...
Thanks, I had forgotten that that issue had been raised, however, there are fewer + ions, the magrid is positive and should repel the + ions (as opposed to attract the electrons), and the positive ions are moving slower. Also, I had thought that + ion loss could be adjusted by lowering the injection rate and depopulating the well. So, it seemed to me that the issue was just a small nagging doubt. Still, testing is everything. And one more thing I would like to point out is that even though WB-8 is in process, WB-8 confinement is listed on the EMC2 web site under the "proven" row of achievements to date. So, I took that as a preliminary result report.Tom Ligon wrote:The question that has been raised is, would not ions follow the electrons right out the cusps?
Counting the days to commercial fusion. It is not that long now.
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Art Carlson
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Since we don't know what the electron losses were from WB-6, it doesn't help much to know that WB-7 "validated" them.mvanwink5 wrote:Tom, I am not understanding the doubts that the polywell is leaking like a sieve because the EMC2 site clearly states that the WB-7 tests validated the electron losses in WB-6. What am I missing?
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Art Carlson
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If I have any "small nagging doubt" (and I'm not sure I do), it is that my analysis might be wrong. If you look through the archives (and have the physics background to follow my arguments and calculations), you will find quantitative estimates of minimum energy loss rates that I think are robust. It is not a pretty sight.mvanwink5 wrote:So, it seemed to me that the issue was just a small nagging doubt.
It is odd that you forgot about that issue. I considered it to be the most important issue regarding the viability of the concept. (Once Art pointed it out a long time ago.) If electrons leak out the Holes, how do you keep the Ions from following them?mvanwink5 wrote:Thanks, I had forgotten that that issue had been raised, however, there are fewer + ions, the magrid is positive and should repel the + ions (as opposed to attract the electrons), and the positive ions are moving slower. Also, I had thought that + ion loss could be adjusted by lowering the injection rate and depopulating the well. So, it seemed to me that the issue was just a small nagging doubt. Still, testing is everything. And one more thing I would like to point out is that even though WB-8 is in process, WB-8 confinement is listed on the EMC2 web site under the "proven" row of achievements to date. So, I took that as a preliminary result report.Tom Ligon wrote:The question that has been raised is, would not ions follow the electrons right out the cusps?
Recirculation of Electrons is fine, but Recirculation of Ions?
Dunno, seems like a deal killer to me.
Art, no disrespect, I understand that you have skill in the theory, but I don't believe R. Nebel is playing with words, but that is just me. Thanks for your reply.
Diogenes, it is not odd, it is just my failing. Perhaps if I had understood your objection better I would have remembered it. Still, I will wait for test results. Thanks for your thoughts.
Diogenes, it is not odd, it is just my failing. Perhaps if I had understood your objection better I would have remembered it. Still, I will wait for test results. Thanks for your thoughts.
Counting the days to commercial fusion. It is not that long now.
Yes but what is proven? That it's not feasible, or still unclear, or clearly feasible? It only means that they've proven their data collection ("confinement behavior and detailed diagnostics") works. The question is what the data says, and the website says nothing about that. Not even qualitatively.mvanwink5 wrote:even though WB-8 is in process, WB-8 confinement is listed on the EMC2 web site under the "proven" row of achievements to date. So, I took that as a preliminary result report.
Last edited by Betruger on Sat Mar 20, 2010 10:01 pm, edited 1 time in total.
Correct me if I'm wrong, but that would mean Dr Bussard's comments e.g. on the Google talk are bogus?Art Carlson wrote:Since we don't know what the electron losses were from WB-6, it doesn't help much to know that WB-7 "validated" them.mvanwink5 wrote:Tom, I am not understanding the doubts that the polywell is leaking like a sieve because the EMC2 site clearly states that the WB-7 tests validated the electron losses in WB-6. What am I missing?